JPS6310310A - Magneto-resistance effect type magnetic head - Google Patents

Abstract

PURPOSE:To reduce the level of an induced unnecessary AC component by connecting a bias conductor to one pair of terminals adjacent to each other and arranging the other pair of terminals adjacent to each other, which a magnetoresistance effect magnetosensitive element is connected to, on the outside of one pair of terminals. CONSTITUTION:A pair of terminals 3a and 3b of a bias conductor 3 are arranged adjacently to each other, and one lead part 3bb is bent to form an about U shape with the bias conductor 3 and is connected to the terminal 3b. Though an MR magnetosensitive element 5 is connected to terminal 5c and 5d in a U shape, these terminals 5c and 5d are arranged on the outside of terminals 3a and 3b for the bias conductor 3. Terminals 22a and 22 of a peripheral circuit part 20 are arranged adjacently to each other in accordance with the arrangement of respective terminals of a head part Hd, and terminals 14c and 14d are arranged on the outside of them and are connected to respective terminals of the head part Hd by a multistripe lead 26. Thus, electromagnetic coupling between a bias system and a signal system is reduced to reduce the level of the induced unnecessary AC component.

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A Industrial application field B Summary of the invention C Prior art D Problem to be solved by the invention E Means for solving the problem (Fig. 1) F Effect G Example G5 - Example (1st t511) ) G2 Other Embodiments (FIG. 2) H Effects of the Invention A Field of Industrial Application The present invention relates to a magnetoresistive magnetic head that uses an alternating current bias magnetic field.

B. Summary of the Invention The present invention provides a magnetoresistive magnetic head using an alternating current bias magnetic field, in which one pair of adjacent terminals to which a signal lead wire of a magnetosensitive element is connected is connected to the other adjacent terminal pair to which a bias lead wire is connected. By arranging it outside the pair, the electromagnetic coupling between the bias conducting wire and the signal leading wire is reduced, and the level of unnecessary AC components generated in the signal leading wire is reduced.

C. Prior Art First, an example of the structure of a conventional magnetoresistive (hereinafter referred to as MR) magnetic head will be described with reference to FIGS. 3 to 5.

In FIG. 3, (11 is a magnetic substrate, for example, N
It is made of i-Zn ferrite, Mn-Zn ferrite, etc., and when the substrate (11) has conductivity, it is coated with an insulating layer (2) of 5i02 etc.
A bias conductor (3) consisting of a strip-shaped conductive film is deposited;
This serves as a path for a bias current to apply a bias magnetic field to an MR magnetic sensing element (5), which will be described later. For example, Ni-
An MR magnetically sensitive cord (5) made of an MR magnetic thin film of Fe-based alloy or N1-Go thread alloy is arranged. A pair of magnetic N (7) made of, for example, Mo permalloy is placed on this MR magnetic sensing element (5) via a thin insulation of 1 m +61.
and (8) are deposited. Ceramic r# (71 and (8
), each end of which has a bias conductor (3) and an MR magnetic sensing element (
5) and constitutes a part of the magnetic circuit as a magnetic core extending in a direction that traverses both. Board (1)
On top is a non-magnetic insulating protection 1td (via 91,
A protective substrate (10) is bonded.

A non-magnetic spacer layer (11) made of, for example, an insulating layer (6) and having a required thickness is interposed between the one magnetic layer (7) and the 11,110,000 ends of the substrate fl). A magnetic gear "is formed. Then, C1 faces M, a root (I), and a spacer layer (11).

The front surfaces of the magnetic layer (7), the protective layer (9) and the protective substrate ('10) are polished to form a surface (12) that faces a magnetic recording medium such as a magnetic tape.

Further, the rear end of the magnetic layer (7) constituting the magnetic gear g and the niJ end of the other magnetic layer (8) are separated by a distance of h, and a discontinuous portion (13) is formed between both ends. Ru. Both magnetic layers (
The rear and front ends of 7) and (8) are covered with an insulating layer (6
), the MR sensing element (5
) at the discontinuity (13). Hidden "C,) J, 4Mto - Magnetic gear g - Magnetic layer + 71 - MR magnetic sensing element (5)
- A magnetic circuit from the magnetic layer (8) to the substrate (11) is formed.

In the M I'<type magnetic heel]' portion Hd, the signal magnetic flux in the front gap g, which is in contact with the magnetic recording medium, flows through the above-mentioned magnetic circuit, thereby increasing the MR sensitivity in this magnetic circuit. The resistance value of the magnetic element (5) changes depending on the external magnetic field caused by this signal magnetic flux. Therefore, a detection current is applied to the MR magnetic sensing element (5), and this change in resistance value is detected by the MR magnetic sensing element (5).
The recorded signal on the magnetic medium is reproduced by detecting the voltage change across the magnetically sensitive element (5).

In this case, in order for the MR magnetic sensing element (5) to operate linearly as a magnetic sensor and to have high sensitivity, it is necessary to magnetically bias the MR magnetic sensing element (5). This bias magnetic field is a DC magnetic field given by a magnetic field generated by energizing the bias conductor (3) and a magnetic field itself generated by the detection current flowing to the MR magnetic sensing element (5).

That is, the MR type magnetic head in this building has an MR sensor 4B and an element (5), as shown in FIG.
The magnetic field generated by applying 1B of direct current to the bias conductor (3) and the MR magnetic sensing element (5) from the constant current source (16)
) The signal magnetic field Hs from the magnetic medium is applied while the bias magnetic field HR is applied by the magnetic field generated by applying the detection current IMR to the magnetic medium. and,
Based on the resistance change caused by this signal magnetic field Hs, the potential change at the midpoint of connection between the MR magnetic sensing element (5) and the constant current source (16), that is, point A, is detected by an amplifier via a low-frequency blocking capacitor C. (14), amplified and outputted from the output terminal (15).

FIG. 5 shows the operating characteristics showing the relationship between the magnetic field H applied to this MR magnetic sensing element (5) and its resistance value R.

This characteristic curve is in the range where the absolute value of the magnetic field H is small (HBR
〜+HRR) shows an upwardly convex quadratic curve, but when the absolute value of the magnetic field H becomes large and deviates from this range, the MR
The magnetization of the central portion of the MR magnetic V# film constituting the magnetosensitive element (5) begins to saturate in the direction of the magnetic circuit, and its resistance value R becomes 2.
It moves away from the next curve and asymptotically approaches the minimum value RIIlin. Incidentally, the maximum value Rwax of this resistance value R is a value in a state where all the magnetization of the MR magnetic thin film is oriented in the current direction.

Then, in the quadratic curve part of this operating characteristic curve,
With the aforementioned bias magnetic field I (R) applied, the fifth
A signal magnetic field from a magnetic medium, which is indicated by the symbol (17) in the figure, is applied, and an output is obtained based on the change in resistance value, which is indicated by the symbol (18) in the figure. . In this case, the larger the signal magnetic field, the larger the second harmonic distortion.

Moreover, the resistance value R of this MR magnetic sensing element (5) is R=Ro
(1+αcos' θ)...(1) (However, Ro
is the fixed resistance value, α is the maximum resistance change rate, and θ is the angle between the current direction and the magnetization direction in the MR magnetic sensing element (5). For example, the MR magnetic sensing element (5) is 81N
+-19Fe (par 70) thickness 250
In the case of a human MR magnetic thin film, the actual value of α is α−0,
It is about 017. The value of this α is the MR magnetic sensing element (5)
The MR magnetic WIJ is approximately α-0.05 at most, although there are some differences depending on the film thickness and material of the crotch. That is, M.R.
The change in resistance value of the borosilicate element (5) is small, about 5% at most.

On the other hand, the fixed portion Ro of this resistance is Ro = Ri (1+aΔt)
...(2+ (where R4 is the initial value of resistance, a is the temperature coefficient, and Δt is the temperature change), and the temperature coefficient a in the example of the MR magnetic sensing element (5) described above is The actual measured value is approximately a = 0.0027/dat:
This is considerably larger than the maximum resistance change rate α mentioned above.

Therefore, the temperature of the head fluctuates due to heat generated by the application of a detection current to the MR magnetic sensing element (5) or the bias current to the bias conductor (3), and the potential at point A fluctuates greatly. .

Furthermore, during operation, heat is radiated unstablely due to the sliding contact with the magnetic recording medium, causing the temperature of the head to change irregularly.
Sliding noise is present.

In order to solve the above-mentioned problems of the conventional MR head using a DC bias magnetic field, the present applicant has proposed
No. 1-54005 (Japanese Patent Application No. 59-176476) has already proposed a 1" magnetoresistive magnetic head device using an alternating current bias magnetic field.

Next, with reference to FIGS. 6 and 7, the above-mentioned AC type MR head apparatus by the present applicant will be explained.

FIG. 6 shows an example of the configuration of a conventional AC type MR head device made by the present applicant. In FIG. 6, parts corresponding to those in FIG. 4 are given the same reference numerals, and redundant explanation will be omitted.

In FIG. 6, the square wave generator (
21) is supplied to the buffer (22), and
It is supplied to the changeover switch (23) as a control signal. The frequency of this rectangular wave is selected to be three times or more the highest frequency of the signal magnetic field Hs. A bipolar rectangular wave bias current iB as shown in the seventh diagram is supplied from the buffer (22) to the bias conductor (3).

Then, connect the bias conductor (3) to the MR magnetic sensing element (5).
The bias magnetic field H8 is applied by the rectangular wave magnetic field generated by the rectangular wave current iB being applied to the MR magnetosensitive element (5) and the magnetic field generated by the detection current 1l-IR being applied to the MR magnetosensitive element (5). Signal magnetic field Hs from magnetic medium
I can get it. Then, ζ, based on the resistance change due to this signal magnetic field Hs, the change in electrification at the connection midpoint between the MR magnetic sensing element (5) and constant current # (16), that is, at point A, is
°ζ is supplied to the amplifier (14). The output of this amplifier (14) is directly supplied to one fixed contact (23a) of the switch (23), and the inverter (2
4) to the other fixed contact (23b),
A negative contact (23c) of the switch (23) is connected to the output terminal (15) via a low-pass filter (25).

The operation of the MR head device shown in FIG. 6 is as follows.

A bias current i of a bipolar rectangular wave such as the '10th wave is applied to the bias conductor (3) of the MR head Hd.

When flowing, +HIl+ appears on the MR magnetic sensing element (5).
The HR bias magnetic field is applied alternately, and the operating point is alternately switched to point P and point Q on the characteristic line shown in FIG. When the signal magnetic field Hs (t) from the magnetic medium is superimposed on this, the magnetic field applied to the MR magnetosensitive element (5) is
As shown in Figure B, the envelopes on the IE side and the negative side wave in the same phase with the period of the signal magnetic field Hs (tl) centering on +Hs and -Ha, respectively, and then with the period of the rectangular wave bias current iB. Switches between both envelopes.

As a result, each time the polarity of the rectangular bias current iB is alternately switched between positive and negative, the output signal component from the MR magnetic sensing element (5) is on the one operating point P side of the characteristic curve shown in FIG. 7A. and the output signal component on the other operating point Q side are alternately output as shown in FIG. This output signal ◎ is asymmetric with respect to the baseline due to the nonlinearity of the characteristic curve.

Since the switch (23) is alternately switched in synchronization with the square wave bias current iH, its movable contact (23c)
In this case, an MR magnetic sensing element (5
) of the output signal ◎, in response to the negative polarity bias current shown in Figure 7, the output signal component at one operating point, e.g., point P, in Figure 7 is reversed in polarity, and the output signal component at the other operating point, For example, it is added to the output signal component on the Q point side in a mutually complementary manner to obtain a synchronized output signal (2) as shown in FIG.

The low-pass filter (25) removes the low-frequency rectangular wave component from this synchronized output signal ■, and the output terminal (15) receives an average of both the signal components on the P point side and the Q point side. , a reproduced signal from which distortion due to non-linearity of the characteristic curve has been removed is output.

In the process of forming the synchronized output signal described above, the polarity of the signal component on one operating point side is inverted and added to the other signal component. This simply means that a differential output of both signal components is obtained. That's true. That is, the above-mentioned AC type MR head device by the applicant uses a relatively large amplitude bipolar rectangular wave bias magnetic field and a polarity inverted output synchronized with this rectangular wave to produce a single MR sensation. A differential MR head is constructed isometrically while having a boron element.

As a result, the nonlinearity of each characteristic curve on the operating point P side and Q side in FIG. 7A is improved, and a reproduced signal without distortion can be obtained.

Further, since the aforementioned temperature drift and sliding noise are in phase with this isometric differential MR head, their effects are sufficiently suppressed.

Furthermore, since the modulation amplification is performed using a square wave, detection of very low frequency magnetic fields including direct current is possible with 1+J capability, and since the frequency of the square wave is selected to be high, coupling is possible even when the input impedance of the amplifier (14) is low. The capacitance of capacitor C can be selected to be small.

D Problems to be Solved by the Invention Incidentally, in the conventional MR head device, as shown in FIG.
A bias conductor (3) is connected to b) in a U-shape, and is connected to the other pair of terminals (5c) and (5d) via signal lead wires (leads > (5cc) and (5dd), respectively). ,
The MR magnetic sensing elements (5) were similarly connected in a U-shape. Lead from MR sensing element (5) (5cc)
, (5dd), usually,
The terminals (5c) and (5d) are arranged inside the terminals (3a) and (3b) for the bias conductor (3).

The peripheral circuit section (20) includes a bias current source (2).
2) a pair of terminals (22a) and (22b) for
A pair of terminals (14c) and (14d) for the amplifier (14) are provided, and a multi-parallel lead such as a flexible printed wiring board is connected between the corresponding terminals of the head portion Hd. Each strand (26a) of (26)
~(26d).

In addition, in FIG. 8, MR1! ! , illustration of a constant current source and a coupling capacitor for passing a detection current through the magnetic element (5) is omitted.

However, the terminals (3a) to (5d) of the MR head Hd
is arranged as shown in Fig. 8, the MR magnetic sensing element (
The output signal path from 5) to the amplifier (14) of the peripheral circuit section (20) via the terminals (5c) and (5d) is from the bias current source (22) to the bias conductor (3) of the head section Hd. It is electromagnetically coupled to the current supply path.

That is, the magnetic flux generated by the bias current io flowing back to the current source (22) via the bias conductor (3) is transmitted to the head HdOMR sensing element (5), the flesh leads (5cc) and (5dd), the terminal (5c) and (5d), inner strands (26c) and (26d) of multi-filament parallel lead (26)
.

Terminals (14c) and (14d) and peripheral circuit section (2)
0) lead (14cc), (14dd) and (
22bb) is interlinked with the signal output loop formed by the terminals (14c) and (14d). This induces an unnecessary alternating current component of the frequency of the bias current in the signal output loop.

As mentioned above, since the frequency of the bias current iB is selected to be quite high, the level of the unnecessary AC component induced in the signal output loop becomes quite large, and there is a risk of saturating the amplifier (14).

Furthermore, this unnecessary AC component causes a significant offset voltage to be generated in the synchronized output signal described above, resulting in a reduction in the dynamic range.

In view of the above, an object of the present invention is to provide a magnetoresistive magnetic head in which unnecessary electromagnetic coupling between a signal output path and a bias current supply path is reduced.

E. Means for Solving the Problems The present invention provides a method in which the signal lead-out lines of magnetoresistive magnetic sensing elements are connected to one pair of terminals arranged adjacent to each other, and a bias magnetic field is applied to the magnetic sensing elements. Bias conductors through which alternating current bias current flows are connected to the other pair of terminals arranged adjacent to each other, and one pair of terminals to which the signal lead-out wire of the magnetosensitive element is connected are connected to the other pair of terminals to which the bias conductor is connected. This is a magnetoresistive magnetic head placed outside the terminal pair.

F Effect According to this configuration, the area of the portion of the output signal path from the magneto-sensitive element where the magnetic flux due to the bias current interlinks is reduced, and the level of the induced unnecessary alternating current component is reduced.

G Embodiment G1-Embodiment Hereinafter, an embodiment of the magnetoresistive magnetic head according to the present invention will be described with reference to FIG.

FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, parts corresponding to those in FIGS. 3 and 8 are given the same reference numerals, and some explanations will be omitted.

In Figure 1, a pair of terminals (3) of a bias conductor (3) are shown.
8) and (3b) are arranged adjacent to each other, one lead part (3bb) is bent to form a substantially rUJ shape with the bias conductor (3), and connected to the terminal (3b). Ru. The MR magnetic sensing element (5) is connected to the terminals (5C) and (5d) in a U-shape as in FIG. 8, but the terminals (5C) and (5d) are connected to the bias conductor ( 3) are arranged outside the terminals (3a) and (3b). Corresponding to the arrangement of the terminals of the head section Hd as described above, the terminals (22a) and (22b) of the peripheral circuit section (20) are arranged adjacent to each other, and the terminals (1) are arranged on the outside thereof.
4c) and (14d) are arranged, and the multi-lead lead (26)
are respectively connected to the respective terminals of the head portion Hd.

With the above configuration, in the embodiment of FIG. 1, °ζ is MR
Among the output signal paths from the magnetic sensing element (5), the MR magnetic sensing element (5) 1 signal derivation 1jt (5cc) and (5dd
) and the signal output loop formed by the lead portion (3bb) of the bias conductor (3), the magnetic flux due to the bias current iB is interlinked.

As is clear from the comparison with FIG. 8, in the embodiment of FIG. 1, the area of the signal output loop interlinked with the magnetic flux due to the bias current iB is significantly reduced. Therefore, electromagnetic coupling between the bias system and the signal system is reduced, and the level of induced unnecessary AC components is reduced, resulting in amplifier saturation and
Problems such as reduction in dynamic range due to offset are resolved.

G2 Other Embodiments Next, with reference to FIG. 2, another embodiment in which the present invention is applied to a multi-track magnetoresistive magnetic head will be described.

The structure of another embodiment of the present invention is shown in FIG. In FIG. 2, parts corresponding to those in FIGS. 1, 3, and 8 are given the same reference numerals, and some explanations will be omitted.

In Figure 2, a pair of terminals (3) of a bias conductor (3) are shown.
a) and (3b) are arranged adjacent to each other, and both lead portions (3aa) and (3bb'') are connected to the bias conductor (3a) and (3b).
) and are respectively bent to form a substantially J-shape and connected to terminals (3a) and (3b). 4 (
tail MR magnetic sensing element (51 ((51) to (54))
As shown in Figure 8, the terminals are connected in a U-shape (5C
) and (5d) to (5j) and (5k), but this terminal (5C) and (5d) to (5j) and (5k) are respectively connected to the terminal (3a) for the bias conductor (3). ) and (3b). Corresponding to the arrangement of the terminals of the head portion Hd as described above, the terminals (22a) and (22b) of the peripheral circuit portion (20) are arranged adjacent to each other, and the terminal (14c) is provided on the outside thereof. and (14d) to (143) and (14k) are arranged,
The multi-lead leads (26) are connected to each terminal of the head portion Hd, respectively.

With the above configuration, in the embodiment shown in FIG. 2, among the output signal paths from the MR magnetosensitive elements (51) to (54),
For example, the lead part (3
The magnetic flux due to the bias current IF1 is intersected only in the small-area signal output loop formed by the aa) and the like.

As in the embodiment of FIG. 1, in the embodiment of FIG. 2 as well, the area of the signal output loop interlinked with the magnetic flux due to the bias current 1B is significantly reduced. For this reason,
Electromagnetic coupling between the bias system and each signal system is reduced, the level of induced unnecessary AC components is reduced, and problems such as amplifier saturation and dynamic range reduction due to offset are solved.

H Effects of the Invention As detailed above, according to the present invention, the bias conductor is connected to one pair of adjacent terminals, and the other pair of terminals adjacent to each other are connected to the magnetic effect type magnetosensitive element.
Since l is placed outside of one pair of terminals, the electromagnetic coupling between the bias system and g system is reduced, and the level of induced unnecessary AC components is reduced. is obtained.

[Brief explanation of the drawing]

FIG. 1 is a line plan view showing the structure of one embodiment of the magnetic hesode according to the present invention, FIG. 2 is a line plan view showing the structure of another embodiment of the present invention, and FIG. 1 is a sectional view showing an example of the configuration of the main parts of a conventional magnetoresistive magnetic head, and FIGS. 4 and 5 are connection diagrams and characteristics for explaining the operating state of the conventional magnetoresistive magnetic head. 6 and 7 are connection diagrams and characteristic curve/waveform diagrams for explaining other operating states of the conventional magnetoresistive magnetic head,
FIG. 8 is a plan view showing a configuration example of a conventional magnetoresistive magnetic head. (3) is a bias conductor, (5) is a magnetoresistive effect type magnetic sensing element, (3a), (3b); (5a),
(5b); ”...(5j) (5k) is a terminal pair, (3aa) and (3bb) are signal lead lines.

Claims (1)

[Claims] Signal lead-out lines of magnetoresistive magnetic sensing elements are connected to one pair of terminals arranged adjacent to each other, and an alternating current bias current is provided to apply a bias magnetic field to the magnetic sensing elements. The bias conductors through which the bias conductors flow are connected to the other pair of terminals arranged adjacent to each other, and the one pair of terminals to which the signal lead-out wire of the magnetosensitive element is connected are connected to the other pair of terminals to which the bias conductor is connected. A magnetoresistive magnetic head characterized by being disposed outside of the magnetoresistive head.